The median divides the income distribution into two equal parts: one-half of the cases falling below the median income and one-half above the median. For households and families, the median income is based on the distribution of the total number of households and families including those with no income. The median income for individuals is based on individuals 15 years old and over with income. Median income for households, families, and individuals is computed on the basis of a standard distribution. (See the "Standard Distributions" section under "Derived Measures".) Median income is rounded to the nearest whole dollar. Median income figures are calculated using linear interpolation. (For more information on medians and interpolation, see "Derived Measures".)

Excerpt from:

Social Explorer; U.S. Census Bureau; American Community Survey 2007-2009 Summary File: Technical Documentation.

This includes the income of the householder and all other individuals 15 years old and over in the household, whether they are related to the householder or not. Because many households consist of only one person, average household income is usually less than average family income. Although the household income statistics cover the past 12 months, the characteristics of individuals and the composition of households refer to the time of interview. Thus, the income of the household does not include amounts received by individuals who were members of the household during all or part of the past 12 months if these individuals no longer resided in the household at the time of interview. Similarly, income amounts reported by individuals who did not reside in the household during the past 12 months but who were members of the household at the time of interview are included. However, the composition of most households was the same during the past 12 months as at the time of interview.

Excerpt from:

Social Explorer; U.S. Census Bureau; American Community Survey 2007-2009 Summary File: Technical Documentation.

The data on race were derived from answers to Question 6. The Census Bureau collects race data in accordance with guidelines provided by the U.S. Office of Management and Budget (OMB), and these data are based on self-identification. The racial categories included in the American Community Survey questionnaire generally reflect a social definition of race recognized in this country, and not an attempt to define race biologically, anthropologically, or genetically. In addition, it is recognized that the categories of the race item include racial and national origin or socio-cultural groups. People may choose to report more than one race to indicate their racial mixture, such as "American Indian" and "White." People who identify their origin as Hispanic, Latino, or Spanish may be of any race.

Race is key to implementing any number of federal programs and it is critical for the basic research behind numerous policy decisions. States require race data to meet legislative redistricting requirements. Also, they are needed to monitor compliance with the Voting Rights Act by local jurisdictions.

Federal programs rely on race data in assessing racial disparities in housing, income, education, employment, health, and environmental risks. Racial classifications used by the Census Bureau and other federal agencies meet the requirements of standards issued by the Office of Management and Budget in 1997 (Revisions to the Standards for the Classification of Federal Data on Race and Ethnicity). These standards set forth guidance for statistical collection and reporting on race and ethnicity used by all federal agencies.

The Census Bureau has included a question on race since the first census in 1790. The racial classifications used by the Census Bureau adhere to the October 30, 1997, Federal Register Notice entitled, "Revisions to the Standards for the Classification of Federal Data on Race and Ethnicity," issued by the Office of Management and Budget (OMB). These standards govern the categories used to collect and present federal data on race and ethnicity. The OMB requires five minimum categories ("White," "Black or African American," "American Indian" or "Alaska Native," "Asian," and "Native Hawaiian" or "Other Pacific Islander") for race. The race categories are described below with a sixth category, "Some other race," added with OMB approval. In addition to the five race groups, the OMB also states that respondents should be offered the option of selecting one or more races.

If an individual did not provide a race response, the race or races of the householder or other household members were assigned using specific rules of precedence of household relationship. For example, if race was missing for a son or daughter in the household, then either the race or races of the householder, another child, or the spouse of the householder were assigned. If race was not reported for anyone in the household, the race or races of a householder in a previously processed household were assigned. This procedure is a variation of the general imputation procedures described in "Accuracy of the Data."

A person having origins in any of the original peoples of Europe, the Middle East, or North Africa. It includes people who indicate their race as "White" or report entries such as Irish, German, Italian, Lebanese, Near Easterner, Arab, or Polish.

A person having origins in any of the Black racial groups of Africa. It includes people who indicate their race as "Black, African American, or Negro," or provide written entries such as African American, Afro-American, Kenyan, Nigerian, or Haitian.

A person having origins in any of the original peoples of North and South America (including Central America) and who maintain tribal affiliation or community attachment. It includes people who classified themselves as described below.

Respondents who identified themselves as "American Indian or Alaska Native" were asked to report their enrolled or principal tribe. Therefore, tribal data in tabulations reflect the written entries reported on the questionnaires. Some of the entries (for example, Metlakatla Indian Community and Umatilla) represent reservations or a confederation of tribes on a reservation. The information on tribe is based on self-identification and therefore does not reflect any designation of federally- or state-recognized tribe. The information for the American Community Survey was derived from the American Indian and Alaska Native Tribal Classification List for the 1990 census that was updated for Census 2000 and the ACS based on the annual Federal Register notice entitled "Indian Entities Recognized and Eligible to Receive Services From the United States Bureau of Indian Affairs," Department of the Interior, Bureau of Indian Affairs, issued by the Office of Management and Budget.

A person having origins in any of the original peoples of the Far East, Southeast Asia, or the Indian subcontinent including, for example, Cambodia, China, India, Japan, Korea, Malaysia, Pakistan, the Philippine Islands, Thailand, and Vietnam. It includes "Asian Indian," "Chinese," "Filipino," "Korean," "Japanese," "Vietnamese," and "Other Asian."

Includes people who indicate their race as "Chinese" or who identify themselves as Cantonese, or Chinese American. In some tabulations, written entries of Taiwanese are included with Chinese while in others they are shown separately.

Includes people who provide a write-in response of an Asian group, such as Bangladeshi, Bhutanese, Burmese, Indochinese, Indonesian, Iwo Jiman, Madagascar, Malaysian, Maldivian, Nepalese, Okinawan, Pakistani, Singaporean, Sri Lankan, or Other Asian, not specified.

A person having origins in any of the original peoples of Hawaii, Guam, Samoa, or other Pacific Islands. It includes people who indicate their race as "Native Hawaiian," "Guamanian or Chamorro," "Samoan," and "Other Pacific Islander."

Includes people who provide a write-in response of a Pacific Islander group such as Carolinian; Chuukese (Trukese); Fijian; Kosraean; Melanesian; Micronesian; Northern Mariana Islander; Palauan; Papua New Guinean; Pohnpeian; Polynesian; Solomon Islander; Tahitian; Tokelauan; Tongan; Yapese; or Other Pacific Islander, not specified. Three Pacific Islander cultural groups are identified in the base tables: Melanesian, which includes Fijian; Micronesian, which includes Guamanian and Chamorro; and Polynesian, which includes Native Hawaiian, Samoan, and Tongan.

Includes all other responses not included in the "White," "Black or African American," "American Indian or Alaska Native," "Asian," and "Native Hawaiian" or "Other Pacific Islander" race categories described above. Respondents providing write-in entries such as multiracial, mixed, interracial, or a Hispanic/Latino group (for example, Mexican, Puerto Rican, or Cuban) in the "Some other race" write-in space are included in this category.

People may have chosen to provide two or more races either by checking two or more race response check boxes, by providing multiple responses, or by some combination of check boxes and write-in responses. The race response categories shown on the questionnaire are collapsed into the five minimum races identified by the OMB, and the Census Bureau's "Some other race" category. For data product purposes, "Two or More Races" refers to combinations of two or more of the following race categories:

White

Black or African American

American Indian and Alaska Native

Asian

Native Hawaiian and Other Pacific Islander

Some other race

There are 57 possible combinations (see Appendix A) involving the race categories shown above. Thus, according to this approach, a response of "White" and "Asian" was tallied as two or more races, while a response of "Japanese" and "Chinese" was not because "Japanese" and "Chinese" are both Asian responses.

Given the many possible ways of displaying data on two or more races, data products will provide varying levels of detail. The most common presentation shows a single line indicating Two or more races. Some data products provide totals of all 57 possible race combinations, as well as subtotals of people reporting a specific number of races, such as people reporting two races, people reporting three races, and so on. In other presentations on race, data are shown for the total number of people who reported one of the six categories alone or in combination with one or more other race categories. For example, the category, "Asian alone or in combination with one or more other races" includes people who reported Asian alone and people who reported Asian in combination with White, Black or African American, Native Hawaiian and Other Pacific Islander, and/or Some other race. This number, therefore, represents the maximum number of people who reported as Asian in the question on race. When this data presentation is used, the individual race categories will add to more than the total population because people may be included in more than one category.

The coding of race write-in entries included an automated review, computer edit, and coding operation. There were two types of coding operations: (1) automated coding where a write-in response was automatically coded if it matched a write-in response already contained in a database known as the master file, and (2) expert coding, which took place when a write-in response did not match an entry already on the master file, and was sent to expert coders familiar with the subject matter. During the coding process, subject-matter specialists reviewed and coded written entries from four response categories on the race question: American Indian or Alaska Native, Other Asian, Other Pacific Islander, and Some other race. All tribal entries were coded as either American Indian or as Alaska Native.

The sequence of the questions on race and Hispanic origin was switched. In the 1996-1998 ACS, the question on race immediately followed the question on Hispanic origin. This approach differed from the 1990 census, where the question on race preceded the question on Hispanic origin with two intervening questions.

The 1990 census category, "Black or Negro" was changed to "Black, African Am."

The 1990 census category, "Other race," was renamed "Some other race." A separate "Multiracial" category was added. The instruction to print the race(s) or group below pertained to both the "Some other race" and "Multiracial" categories.

The "Indian (Amer.)," "Other Asian/Pacific Islander," "Some other race," and "Multiracial" response categories all shared a single write-in area.

1999-2002 American Community Survey

The response category "Black, African Am." was changed to "Black, African Am., or Negro" to correspond with the Census 2000 response category.

The separate 1990 census and 1996-1998 ACS response categories "Indian (Amer.)," "Eskimo," and "Aleut," were combined into one response category, "American Indian or Alaska Native." Respondents were asked to print name of enrolled or principal tribe on a separate write-in line to correspond with the Census 2000 response category.

The 1990 "Asian or Pacific Islander" category was separated into two categories, "Asian and Native Hawaiian" or "Other Pacific Islander." Also, the six detailed Asian groups were alphabetized; and the three detailed Pacific Islander groups were alphabetized after the Native Hawaiian response category.

The response category "Hawaiian" was changed to "Native Hawaiian." The response category "Guamanian" was changed to "Guamanian or Chamorro." The response category "Other Asian/Pacific Islander" was split into two separate response categories, "Other Asian," and "Other Pacific Islander." These changes correspond to those in the Census 2000 response categories.

The separate multiracial response category was dropped. Rather, respondents were instructed to "Mark [x] one or more races" to indicate what this person considers himself/herself to be. Respondents were allowed to select more than one category for race in Census 2000.

In the American Community Survey, the "Other Asian," "Other Pacific Islander," and "Some other race" response categories shared the same write-in area. On the Census 2000 questionnaire, only the Other Asian and Other Pacific Islander response categories shared the same write-in area, and the Some other race category had a separate write-in area.

2003-2007 American Community Survey

The response category "Black, African Am., or Negro" was changed to "Black or African American."

Puerto Rico Community Survey, starting in 2005:

Separate questions on race and Hispanic origin were included on the questionnaire. These questions were identical to the questions used in the United States.

2008-2009 American Community Survey

The wording of the race question was changed to read, "What is Person 1s race?" "Mark (X) one or more boxe"s and the reference to what this person considers him/herself to be was deleted.

The response category "Black or African American" was changed to "Black, African Am., or Negro."

Examples were added to the "Other Asian" response categories (Hmong, Laotian, Thai, Pakistani, Cambodian, and so on) and the "Other Pacific Islander" response categories (Fijian, Tongan, and so on).

Beginning in 2006, the population in group quarters (GQ) is included in the ACS. Some types of GQ populations may have race distributions that are different from the household population. The inclusion of the GQ population could therefore have a noticeable impact on the race distribution. This is particularly true for areas with a substantial GQ population.

The data on race in the American Community Survey are not directly comparable across all years. Ongoing research conducted following the 1990 census affected the ACS question on race since its inception in 1996. Also, the October 1997 revised standards for federal data on race and ethnicity issued by the OMB led to changes in the question on race for Census 2000. Consequently, in order to achieve consistency, other census-administered surveys such as the ACS were modified to reflect changes required by OMB. See the 2009 Code List for Race Code List.